Workers in the item-transport arts are aware of the need for better means to monitor item-movement for instance, such can now be commonly done with optical sensors placed in the item path and used to detect leading and trailing edges of a passing item. But such optical sensors would not be used to measure document thickness. Document thickness information is useful for the employment of downstream "smart" devices that can adjust their parameters so that documents are handled more reliably. Such optical sensors can be located in the guide-walls of a transport track--but, there, they can catch leading edges of documents and cause jams, and/or they can malfunction because of paper dust collecting on them.
This invention is directed toward alleviating the foregoing difficulties. This invention is not sensitive to paper dust; e.g., because it uses idler-monitoring transducer (sensor) means that is not interposed in the document transport path, and because such can be totally enclosed protectively (e.g., by different means known to those familiar with the art). With such an idler-monitoring sensor (not located in the document path), the risk of document jam is reduced or eliminated, and reliable document handling is promoted.
"Idlers" (Idler pinch rollers) are commonly used in document transports in conjunction with a fixed drive roller (e.g., as in FIG. 1). A passing document will thrust an idler roller transversely (i.e., normal to the document transport path) to accommodate various document thicknesses. An object hereof is to operatively associate such an idler roll with a pivot arm and related detector (sensor) means to detect the degree of arm-displacement caused by a passing document; e.g., doing so to obtain various data about the passing document from such a detector (i.e. sensor for "idler transducer"); also, desirably one can locate such a transducer well out of the document path, and can employ a variety of different kinds of transducers to sense such arm-displacement. In this way, this invention will not rely on detect means to directly sense the presence or condition of a document; also, the electrical output from such a transducer can be used to measure document thickness and to detect passage of its leading and trailing edges.
A system according to this invention can detect leading and trailing edges of documents, and document thickness, with a single transducer. Also, various electrical utilization circuits can use the electrical output of the transducer for indicating document presence and/or condition. Such a transducer can operate very simply and reliably, merely measuring the displacement of an idler pinch roller by a passing document.
This invention takes advantage of elements that already exist and uses this idler-displacement as information that can be processed to obtain additional information about the document: e.g., location of leading and trailing edges, length of document, document thickness, interdocument spacing, etc. Worker will realize that this invention can be used for document sorters, mail sorters, copiers, punch card transports, envelope stuffing machines, money feeders, and automatic teller machines.
Thus, another object is to alleviate at least some of the foregoing problems and effect at least some of the foregoing results. A related object is to do so for an set of transport rollers used to advance documents or the like; especially where an idler roll is mounted on mount means whose displacement may be monitered to indicate document size, condition, etc.